Image-rendering devices such as, for example, monitors, scanners, and printers often impose distortions on the color characteristics of a rendered image. Hence, matching of color appearance between images and documents transferred among any combination of the digital image rendering devices requires the use of specialized color image processing knowledge regarding the color rendering characteristics associated with different imaging devices. A CMS (Color Management System) is necessary because different imaging devices have different color capabilities, describe color characteristics in varying terms, and operate among variable color spaces. Such systems generally depend upon standard data structures known as color profiles to determine how to process image pixels.
Photo-product production in retail environments is a significant business opportunity; however, such an environment is very cost sensitive and places a premium on ease-of-use for low-skilled operators. Maximizing the apparent color gamut is very important when producing image centric custom photo-products where end users generally compare the results to silver halide prints. ICC (International Color Consortium) profiles are a professional color management solution and follow an international and accepted standard to enable accurate printed color for all colors that the rendering devices can reproduce. In contrast, achieving accurate color via manual tweaking is nearly impossible due to the complex nature of the rendering device color response. ICC profiles offer the ability to manage color properly to ensure accurate output on various devices. Custom ICC printer profiles can dramatically improve the apparent color gamut of color rendering devices as compared to fleet profiles.
In a CMS and related components and devices, when the dynamic range in the destination space is smaller than that in the source space, use of the relative colorimetric rendering intent will cause dipping in the gamut mismatched area. Although in this case, use of perceptual rendering intent will generally produce better results due to the compression around the gamut boundary, it still causes loss of shadow detail due to the fact that multiple colors in the shadow area will be compressed to the similar color. Use of black point compensation (BPC) can recover some shadow detail by compensating for the L*min in the destination space and moving the mapped L* to a lighter point depending on the pre-mapped L* value. However, BPC sometimes produces overly saturated appearance in the compensated image content due to current approach of preservation of a* and b*. (By this it is meant a* and b* maintain initial values while L* is compressed upward resulting a higher L* value).